The ultimate goal of our research program is to develop tactual aids for the deaf and deaf-blind that can serve as substitutes for hearing in speech communication. To the extent that this research is successful, it will enable people who are deaf to achieve substantially improved speech perception, speech production, and overall language competence. In addition, it will provide increased knowledge about the basic nature of speech communication, about the general capabilities of the tactual sense, about underlying principles for the design of displays, and about sensory substitution and human plasticity. Past work with the deaf and deaf-blind has clearly demonstrated that the tactual sense (by itself, as well as in combination with visual speechreading) can provide good speech reception by means of direct physical contact with the transmitting effectors (e.g., the face of the talker using regular speech, or the hands of the individual using sign language, fingerspelling, or Cued Speech). The task now facing investigators is to develop devices for transforming acoustical signals to patterns of tactual stimulation that will produce equivalent levels of speech reception without such contact (i.e., at a distance). The research proposed in this application is divided into three parts. The first is directed towards the development and evaluation of improved tactual displays and includes study of devices that (as in the direct-contact methods) stimulate the proprioceptive as well as cutaneous sensory systems. The second is focused on tactual supplements to lipreading and includes study of two types of systems: acoustic-based and articulatory-based. Unlike the former, which involves extraction and presentation of signal envelopes, formant frequencies, and/or fundamental frequency, the latter includes a simplified speech-recognition system as a front-end processor and thus involves automated decision making and discontinuous transformations from the acoustic domain to the tactual domain. The third is concerned with comparative study of tactual aids and cochlear implants, and involves study of individuals who have previously been outfitted with a tactual aid or cochlear implant, as well as individuals having no previous experience with such prostheses. Special features of this third project area include testing of tactual aids on people who have previously been implanted with a cochlear prosthesis and field testing tactual aids that are multichannel.